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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Design and development of a remote monitoring system for fuel cells

Komweru, Laetitia 07 1900 (has links)
M. Tech. (Engineering, Electrical, Department Applied Electronics and Electronic Communication, Faculty of Engineering and Technology) -- Vaal University of Technology / This dissertation presents the design and development of a remote monitoring system (RMS) for polymer electrolyte membrane fuel cells (PEMFC) to facilitate their efficient operation. The RMS consists of a data acquisition system built around the PIC 16F874 microcontroller that communicates with a personal computer (PC) by use of the RS232 serial communication standard, using a simple wired connection between the two. The design also consists of a human machine interface (HMI) developed in Visual Basic 6.0 to provide a platform for display of the monitored parameters in real time. The first objective was to establish performance variables and past studies on PEM fuel cells revealed that variables that affect the system's performance include: fuel and oxidant input pressure and mass flow rates as well as operation temperature and stack hydration. The next objective was to design and develop a data acquisition system (DAS) that could accurately measure the performance variables and convey the data to a PC. This consisted of sensors whose outputs were input into two microcontrollers that were programmed to process the data received and transfer it to the PC. A HMI was developed that provided graphical display of the data as well as options for storage and reviewing the data. The developed system was then tested on a 150Watt PEM fuel cell stack and the data acquisition system was found to reliably capture the fuel cell variables. The HMI provided a real-time display of the data, with alarms indicating when set minimums were exceeded and all data acquired was saved as a Microsoft Excel file. Some recommendations for improved system performance are suggested. / Vaal University of Technology -- National Research Foundations
42

Solar Tent : A Photovoltaic Generator Model for a Flexible Fabric with Inbuilt Cells

Manhal, Ali, M. Ali, Tammam January 2019 (has links)
Natural disasters and conflicts in many different parts of the world force thousands of people to get displaced from their homes and live in refugee camps temporarily or permanently. For refugee families, lack of energy access has great impact on their lives. Tarpon Solar Company has developed a solar tent which is a combination of laminated cloth and flexible solar cells. In addition to producing renewable electricity, it can create a comfortable outdoor shelter from sun, rain and wind.   The aims of this study were to define and size the solar system of the tent in both AC and DC systems and optimize the tent to work in different locations around the world. Besides designing a monitoring system for the solar tent to evaluate the performance. In addition, defining the social aspect and the consumer behavior for a better solar tent future design. As a case study, Tarpon AC solar tent in Glava, Sweden has been installed to cover the basic needs of the tent users. To understand the solar tent performance in different weather zones, 4 different locations were suggested. A monitor system was designed to monitor the tent solar system performance. The simulation software PVsyst was used to size the PV system in the different locations with different solar data.   The PVsyst simulation results showed that the current Tarpon solar tent with 32 photovoltaic modules is extremely oversized to cover the basic needs loads (Lighting, mobile charging and ventilation) in the emergency cases.   The current Tarpon solar tent has a standard number of photovoltaic modules integrated in the tent fabric while the photovoltaic modules number should vary from one location to another according to the weather data and solar irradiation. In this case the current Tarpon solar system used in Glava, Sweden can be optimized by decreasing the number of photovoltaic modules to only 6 photovoltaic modules instead of 32 modules.   The study also shows that the features of the off-grid system components (battery and charge controller) are different from one location to another according to the criteria of selection.   This study concludes that for the temporary short-term emergency use of the tent where only basic needs loads are needed, DC system is better than AC system in terms of energy efficiency, system size and cost in the different proposed locations. While AC system is better when using the tent for prolonged time in terms of user flexibility and ability to extend the system. Understanding the consumer behavior and the goal of the tent whether to be used for an emergency short term shelter or a permanent shelter for a prolonged time are important factors for a better solar tent design.
43

Problem prevention using the DCOV approach : A case study on a camera monitoring system at Volvo Cars

Larsson, Carl, Magnusson, Martin January 2019 (has links)
The Swedish car manufacturer, Volvo Cars, are a pioneer in the automotive industry regarding vehicle safety. Ever since they invented the three-point seat belt, the safety aspect has been their main priority. Today, a car is equipped with new technology and is highly dependent on software solutions. This implies that software features are used to increase the safety of the car. The level of uncertainty increases with the new features, which highlights the importance of creating a robust product to avoid potential problems. During the last decade, the DCOV approach (Define – Characterize – Optimize – Verify) evolved to create a product that is insensitive to variation and appreciated by the customers. Volvo Cars are currently developing a camera monitoring system (CMS) that is supposed to replace the conventional rear-view mirror with an exterior camera and an interior display. The purpose of this master’s thesis is to develop a robust design for the CMS that satisfies the customers. By using the DCOV approach, the aim is to identify potential risks and failure modes to avoid hardware and software related problems, and at the same time, develop a product that is based on the voice of the customer. This thesis demonstrates the problems with the conventional mirrors and the parking assistance cameras, which are associated with the folding function, the mirror adjustment, and the wide-angle module. The analysis of customer surveys indicates that blind spot indicators are appreciated by the customers while the mirror size is a critical factor. The mirrors need to be large enough to provide a good rear-view visibility, but small enough to maintain good forward visibility. A parameter diagram, robustness checklist and a system failure mode and effect analysis (S-FMEA) were conducted to identify risks, noise factors and failure modes with the CMS. It resulted in 44 failure modes where six of them were considered as critical, which means a high level of severity or frequent occurrence. The six critical failure modes were identified at the S-FMEA meetings with the business units Manufacturing, Display systems, Electromagnetic compatibility and CMS camera. Three business units were software related, which shows the difficulties with the transition from a hardware related rear-view mirror to the CMS. The recommendations for Volvo Cars are divided into two categories, where the first is associated with the CMS and should be seen as a continuation of this thesis. Volvo Cars should complete the S-FMEA and the included actions. By conducting the recommendations for the CMS, it will be properly tested to resist noise factors and manage potential variation. The long-term recommendations are proposals for future actions, which include a CMS for the inner mirror and investigate BLIS options. If the recommendations are considered, it will increase the possibility of creating a robust design, based on the voice of the customer. The result of this study highlights the power of the DCOV approach, as it clearly shows that it is possible to reduce the warranty costs. If the folding function is excluded, and the CMS software becomes easy to update, the warranty costs could be reduced by SEK 5 million.
44

Arquiteturas para monitoramento e supervisão integrados de processos de usinagem em máquinas com controle numérico aberto / Integrated monitoring and supervision architectures applied to machining process controlled by open CNC systems

Ferraz Júnior, Fábio 14 August 2007 (has links)
Empreendimentos industriais requerem o completo e preciso acompanhamento de dados de máquinas em tempo real, integrando as atividades do chão de fábrica com a engenharia, suporte e de negócios. É reconhecido que sistemas de monitoramento são fundamentais para melhorar a qualidade do produto, reduzir os tempos e para a adaptação rápida às mudanças de produção. Os sensores de processos possuem altos custos, não são compactos e são de difícil implementação. Portanto, seria estratégico desenvolver sistemas de monitoramento que utilizem ao máximo os recursos já existentes nas máquinas ferramentas e que não representem custos adicionais de implementação. O uso de CNC´s de arquitetura aberta nas indústrias é crescente. Estes se mostram como potenciais ferramentas para atender a estas exigências. Possuem os recursos necessários para a aquisição de informações administrativas e tecnológicas e para o desenvolvimento de sistemas de monitoramento. O objetivo do presente trabalho é pesquisar arquiteturas de monitoramento e supervisão para processos de usinagem que tenham como base informações disponíveis em CNC´s de arquitetura aberta. Tais sistemas, apesar de todo o potencial existente, ainda não tem sido explorados nem desenvolvidos adequadamente para os processos de usinagem. O presente trabalho é multidisciplinar nas áreas de automação e usinagem. Está dividido em partes em que são analisados tanto os elementos tecnológicos dos CNC´s abertos, bem como os processos de monitoramento e supervisão da usinagem. São apresentadas propostas no sentido de integrar as duas áreas pelo desenvolvimento de arquiteturas de software dedicadas. Os sistemas desenvolvidos foram testados em laboratório e também nas empresas parceiras. Os resultados mostram que o uso de CNC´s abertos para monitoramento e supervisão de processos é viável e proporciona funções de monitoramento/supervisão que não eram possíveis com os sistemas convencionais e sem a necessidade de recursos adicionais, como hardware, sensores e instalação. A implementação de protótipo em empresa parceira foi bem sucedida e deverá ser expandida no futuro. / Manufacturing enterprises require complete real time and accurate monitoring of machine tool data for integrating the shop floor with other company activities, as engineering, maintenance and business. It is acknowledged that monitoring systems capabilities are unavoidable to improve product quality, to reduce production time, and to the rapid adaptation in the changes of production. The use of external sensors gives high costs and do not have the advantages of compactness and the ease of use. Therefore, it is extremely advantageous to develop monitoring systems maximizing the use of the resources already existent in the machine tools and without additional costs of implementation. The use of open CNC\'s on industries is growing. This kind of control has been a great tool to attend these present requirements. It has the necessary resource to get managerial and technological information, and to develop monitoring systems. The objective of this work is to research monitoring and supervision architectures for machining process, based on information already available in open CNC\'s. Such systems, in spite of the whole existent potential, have not still been explored nor developed appropriately for the machining processes. The present work is multidisciplinary in the automation and machining areas. It is divided in parts where the technological elements of open CNC\'s are analyzed, as well as the monitoring and supervision systems of the machining processes. An architecture is proposed in the sense of integrating both monitoring and supervision. The developed systems were tested in laboratory and also in the partner companies. The results show that the use of open CNC\'s for monitoring and supervision of processes is viable and provides monitoring/ supervision functions which were not possible with the conventional systems and without the need of additional resources, as hardware and sensor installation. The prototype tested in a partner company succeeded and should be expanded in the future.
45

Detection of erosion/deposition depth using a low frequency passive radio frequency identification (rfid) technology

Moustakidis, Iordanis Vlasios 01 December 2012 (has links)
This thesis presents an experimental study both in the laboratory and field to develop and test a method for continuously measuring and monitoring scour using an automated identification technology known as Radio Frequency Identification (RFID). RFID systems consist of three main components, namely (a) the reader which controls the system, (b) the transponder (derived from transmitter/responder) that transmits data to the reader and (c) the excitation antenna that allows the communication between the reader and the transponder. The study provides an insight into the RFID technology and develops the framework for using this technology to eventually address two central themes in river mechanics and sediment transport; (a) the determination of the active layer thickness and (b) the scour/deposition depth around a hydraulic structure. In particular, this study develops the methodology for relating the signal strength of a radio frequency (RF) device with the distance between an excitation antenna and the RF device. The experiments presented herein are classified into two main groups, (1) the laboratory and (2) the RF signal vs. the detection distance experiments (field experiments). The laboratory experiments were designed to understand the effect of key RFID parameters (e.g., transponder orientation with respect to the excitation antenna plane, maximum antenna-transponder detection distance), measured in terms of the transponder return RF signal strength for various antenna-transponder distances, transponder orientations with respect to the excitation antenna plane and different mediums in between the excitation antenna and the transponder, on the overall performance of the RFID system. On the other hand, the RF signal vs. the detection distance experiments were based on the results obtained during the laboratory experiments and focused on developing calibration curves by relating the transponder return RF signal strength with the distance between the excitation antenna and a transponder. The laboratory results show that the dominant RFID parameters affecting the system performance are (a) the transponder orientation towards the excitation antenna plane and (b) the medium type in between the excitation antenna and the transponder. The differences in reading distances were attributed to the transponder inner antenna type, while the effect of the medium was related with the void ratio, where higher porosity materials have, less RF signal strength decay. The parameter that governs the RF signal strength decay was found to be the distance between the excitation antenna and the transponder (erosion process experiments). The RF signal strength decays almost linearly with distance, while the rate of the RF signal strength decay is controlled by the material type in between the excitation antenna and the transponder (deposition process experiments). The RF signal vs. the detection distance experiments demonstrate that the reading distance of the RFID system can be significantly increased by using a custom made excitation antenna. The custom made excitation antenna not only increases the reading distance between the antenna and the transponder to nearly 20 ft., but also allows the user to manipulate the excitation antenna's shape and size to meet the specific landscape requirements at the monitoring site.
46

Power Analysis of Continuous Data Capture in BeePi, a Solar- Powered Multi-Sensor Electronic Beehive Monitoring System for Langstroth Beehives

Shah, Keval 01 May 2017 (has links)
This thesis describes the power analysis of the electronic beehive monitoring system. The electronic beehive monitoring system was made to work either with a UB12120 12V 12Ah standard lead-acid battery or an Anker (TM) Astro E7 5V lithium-ion battery to analyze the power requirements. These batteries are recharged by Renogy 50Watt 12 Volt Monocrystalline Solar Panel. Power analysis is performed using both batteries to calculate system’s efficiency. The performed power analysis indicates that the Anker (TM) Astro E7 26800mAh 5V lithium-ion battery runs approximately 6 hours more than the lead acid battery. Moreover, the lithium-ion battery is compact, has a lighter weight, is more efficient, and has a longer cycle life. Using lithium-ion batteries will likely result in fewer hardware components and a smaller environmental footprint.
47

Development and Evaluation of a BlackBerry-based Wearable Mobility Monitoring System

Wu, Hui Hsien 05 January 2012 (has links)
A Wearable Mobility Monitoring System (WMMS) can be an advantageous device for rehabilitation decision-making. This thesis presents the design and evaluation of a proof-of-concept WMMS that uses the BlackBerry Smartphone platform. A Java program was developed for the BlackBerry 9550, using the integrated tri-axial accelerometer, Global Positioning System sensor (GPS), CMOS digital video camera, and timer to identify change-of-state (CoS) among static states, dynamic states, small activity of daily living (ADL) movements, and car riding. Static states included sitting, lying, standing, and taking an elevator. Dynamic states included walking on level ground, walking on stairs, and walking on a ramp. Small activity of daily living movements included bathroom activities, working in the kitchen, and meal preparation. Following feature extraction from the sensor data, two decision trees were used to distinguish CoS and mobility activities. CoS identification subsequently triggered video recording for improved mobility context analysis during post-processing.
48

A Monitoring System to Reduce Shoulder Injury Among Construction Workers

Alwasel, Abdullatif January 2011 (has links)
As the work force ages and workers retirement age increases, the number of workers suffering from Work-related Musculoskeletal Disorders (WMSDs) has increased. In a recent study, the U.S Bureau of Labor reported that 6.9% of all WMSDs affected shoulders. Electricians, carpenters, and related construction crafts appear to experience higher incidence of these injuries due the nature of their work that require them often to use Awkward shoulder postures. This research aims to develop a new monitoring system that measure the amount of time workers spend in awkward shoulder postures to help decrease the prevalence of cumulative shoulder injuries and to reduce the number of cases of shoulder WMSDs among construction workers. The monitoring system was designed and a feasibility study was conduct to compare the monitoring system with a state of the art motion tracking system. Overall the monitoring system was able to count the time spent in awkward posture as a discrete state sensor and it can be implemented in the field. However, results showed that the monitoring system in its current configuration require some future work for it to produce quantitatively precise results that can be used in the fields of biomechanics, robotics, and ergonomics.
49

Development and Evaluation of a BlackBerry-based Wearable Mobility Monitoring System

Wu, Hui Hsien 05 January 2012 (has links)
A Wearable Mobility Monitoring System (WMMS) can be an advantageous device for rehabilitation decision-making. This thesis presents the design and evaluation of a proof-of-concept WMMS that uses the BlackBerry Smartphone platform. A Java program was developed for the BlackBerry 9550, using the integrated tri-axial accelerometer, Global Positioning System sensor (GPS), CMOS digital video camera, and timer to identify change-of-state (CoS) among static states, dynamic states, small activity of daily living (ADL) movements, and car riding. Static states included sitting, lying, standing, and taking an elevator. Dynamic states included walking on level ground, walking on stairs, and walking on a ramp. Small activity of daily living movements included bathroom activities, working in the kitchen, and meal preparation. Following feature extraction from the sensor data, two decision trees were used to distinguish CoS and mobility activities. CoS identification subsequently triggered video recording for improved mobility context analysis during post-processing.
50

A Distributed and Heuristic Policy-based Management Architecture for Large-Scale Grids

Magaña Perdomo, Edgar 30 May 2008 (has links)
The aim of this thesis is to design and implement a new Grid Resource Management methodology, where non-massive resources owners would be able to share their resources and integrate human collaboration across multiple domains regardless of network technology, operative platform or administrative domain.This thesis proposes a distributed and heuristic policy-based resource management architecture for large-scale Grids. The resource management architecture proposed herein is composed of four main building blocs: services management, resource discovery and monitoring, resource scheduling and jobs allocation and activation. The Grid Services Management (GSM) and Jobs Allocation and Activation (JAA) are supported by means of a Policy-based Grid Resource Management Architecture (PbGRMA). This architecture is able to identify service needs arising from diverse sources during the deployment and management of Grid Services, such as requirements demanded by customers, applications and network conditions. Afterwards, the PbGRMA merges these requirements into deployment policies for the corresponding Grid Services. The Grid Resource Discovery and Monitoring (GRDM) is supported by the introduction of the SNMP-based Balanced Load Monitoring Agents for Resource Scheduling (SBLOMARS), in which network and computational resources are monitored by distributed agents. This allows for a flexible, heterogeneous and scalable monitoring system. The Grid Resource Scheduling (GRS) is based on the Balanced Load Multi-Constrained Resource Scheduler (BLOMERS). This heuristic scheduler represents an alternate way of solving the inherent NP-hard problem for resource scheduling in large-scale distributed networks by means of the implementation of a Genetic Algorithm.Finally, based on the outcome of both the GRDM and GRS, the PbGRMA allocates the corresponding Grid Services by means of its interfaces with Globus ToolKit Middleware and Unix-based CLI commands along of any large-scale Grid Infrastructure. The synergy obtained by these components allows Grid administrators to exploit the available resources with predetermined levels of Quality of Service (QoS), reducing computational costs and makespan in resource scheduling while ensuring that the resource load is balanced throughout the Grid. The makespan of a schedule is the time required for all jobs to be processed when no one job could be interrupted during its execution and each node can perform at most one operation at any time.This new approach has been successfully tested in a real large-scale scenario such as Grid5000. The results presented along this Thesis show that our general solution is a reliable, flexible and scalable architecture to deploy and manage Grid Services in large-scale Grid Infrastructures. Moreover, the substitution of the heuristic algorithm approach used into the Grid Resource Scheduling (GRS) phase by other non-heuristics selection algorithms could make our solution useful in smaller Grid Infrastructures.

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